LINQ - 将号码存储为字符串

问题描述

我有以下数据：

PK    OrderNumber      USERDEFFIELD
1     0001             10
2     0001             25
3     0002             20
4     0002             22
5     0002             NULL
6     0003             ABC123

UserDefField列在数据库中为VARCHAR类型。使用LINQ，如何获得每个订单的SUM（UserDefField）？ UserDefField的NULL和非数值值被认为是零。结果我试图得到：

The UserDefField column is of VARCHAR type in the database. Using LINQ, how can I get the SUM(UserDefField) per order? NULL and non-numeric values for UserDefField are to be considered as zero. The result I'm trying to get:

OrderNumber  TotalQty
0001         35
0002         42
0003          0

如果UserDefField是严格为空的数字字段我知道我会在foreach循环中执行此操作：

If UserDefField is strictly nullable numeric field I know I would do this inside a foreach loop:

 TotalQtyForThisOrder = orders.Sum(w => w.UserDefField ?? 0 );

但是对于字符串字段，应该做什么？非常感谢您的帮助。

But for a string field, what should be done? Thank you very much for the help.

推荐答案

TotalQtyForThisOrder = orders.Sum( w = > {
            int result;
            Int32.TryParse(w.UserDefField, out result);
            return result;
});

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